Bio-functionalization of inner surfaces of all silica Hollow Core–Photonic Crystal Fibers (HC-PCF) has been
investigated. The approach is based on layer-by-layer self-assembly Peptide Nucleic Acid (PNA) probes, which is an
oligonucleotide mimic that is well suited for specific DNA target recognition. Two kinds of HC-PCFs have been
considered: a photonic Bragg fiber and a hollow core (HC-1060) fiber. After spectral characterization and internal
surface functionalization by using PNA probes, genomic DNA solutions from soy flour were infiltrated into the fibers.
The experimental results indicate that hybridization of the complementary strand of target DNA increases the thickness
of the silica layer and leads up to the generation of surface modes, resulting in a significant modulation of the
transmission spectra. Numerical analysis confirms such behavior, suggesting the possibility to realize biological
We describe a novel sensing approach based on a functionalized microstructured optical fiber-Bragg grating for specific DNA target sequences detection. The inner surface of a microstructured fiber, where a Bragg grating was previously inscribed, has been functionalized by covalent linking of a peptide nucleic acid probe targeting a DNA sequence bearing a single point mutation implicated in cystic fibrosis (CF) disease. A solution of an oligonucleotide (ON) corresponding to a tract of the CF gene containing the mutated DNA has been infiltrated inside the fiber capillaries and allowed to hybridize to the fiber surface according to the Watson-Crick pairing. In order to achieve signal amplification, ON-functionalized gold nanoparticles were then infiltrated and used in a sandwich-like assay. Experimental measurements show a clear shift of the reflected high order mode of a Bragg grating for a 100 nM DNA solution, and fluorescence measurements have confirmed the successful hybridization. Several experiments have been carried out on the same fiber using the identical concentration, showing the same modulation trend, suggesting the possibility of the reuse of the sensor. Measurements have also been made using a 100 nM mismatched DNA solution, containing a single nucleotide mutation and corresponding to the wild-type gene, and the results demonstrate the high selectivity of the sensor.
A novel DNA sensing platform based on a Peptide Nucleic Acid - functionalized Microstructured Optical Fibers gratings has been demonstrated. The inner surface of different MOFs has been functionalized using PNA probes, OligoNucleotides mimic that are well suited for specific DNA target sequences detection. The hybrid sensing systems were tested for optical DNA detection of targets of relevance in biomedical application, using the cystic fibrosis gene mutation, and food-analysis, using the genomic DNA from genetic modified organism soy flour. After the solutions of DNA molecules has been infiltrated inside the fibers capillaries and hybridization has occurred, oligonucleotidefunctionalized gold nanoparticles were infiltrated and used to form a sandwich-like system to achieve signal amplification. Spectral measurements of the reflected signal reveal a clear wavelength shift of the reflected modes when the infiltrated complementary DNA matches with the PNA probes placed on the inner fiber surface. Measurements have also been made using the mismatched DNA solution for the c, containing a single nucleotide polymorphism, showing no significant changes in the reflected spectrum. Several experiments have been carried out demonstrating the reproducibility of the results and the high selectivity of the sensors, showing the simplicity and the potential of this approach.
In this work the inner surface of a microstructured optical fiber, where a Bragg grating was previously inscribed, has
been functionalized using peptide nucleic acid probe targeting a DNA sequence of the cystic fibrosis disease. The
solution of DNA molecules, matched with the PNA probes, has been infiltrated inside the fiber capillaries and
hybridization has been realized according to the Watson - Crick Model. In order to achieve signal amplification,
oligonucleotide-functionalized gold nanoparticles were then infiltrated and used to form a sandwich-like system.
Experimental measurements show a clear wavelength shift of the reflected high order mode for a 100 nM DNA solution.
Several experiments have been carried out on the same fiber using the identical concentration, showing the same
modulation and proving a good reproducibility of the results, suggesting the possibility of the reuse of the sensor.
Measurements have been also made using a 100 nM mis-matched DNA solution, containing a single nucleotide
polymorphism, demonstrating the high selectivity of the sensor.
The growing demand for high productivity in the thin-film photovoltaic module industry, together with the request for more and more efficient devices, needs high-performance laser-scribing. The results of scribing tests on CdTe and CIGS solar cells samples are here presented. A comparison between the scribes obtained with ns regime fiber lasers, and a ps regime diode pumped solid state laser will be also reported.
The effects of thermally-induced refractive index change on the guiding properties of different large mode area fibers have been numerically analyzed. A simple but accurate model has been applied to obtain the refractive index change in the fiber cross-section, and a full-vector modal solver based on the finite-element method has been used to calculate the guided modes of the fibers operating at high power levels. The results demonstrate that resonant structures added to the fiber cross-section can be exploited to provide efficient suppression of high-order modes with a good resilience to thermal effects.
We report a grating-less, in-fibre magnetometer realised in a polymethylmethacrylate (PMMA) microstructured optical
fibre that has been infiltrated using a hydrocarbon oil based ferrofluid. The lossy magnetic fluid has been infiltrated by
capillarity action into the microcapillaries of the fiber cladding, resulting in a generation of a short cut-off band located
in the vicinity of 600nm. When the magnetic field is applied perpendicular to the fiber axis, the ferrofluid undergoes
refractive index and scattering loss changes, modulating the transmission properties of the infiltrated microstructured
fibre. Spectral measurements of the transmitted signal are reported for magnetic field changes up to 1300Gauss,
revealing a strong decrease of the signal near its bandgap edge proportionally with the increase of the magnetic field.
Instead, when the magnetic field is applied with respect to the rotational symmetry the fibre axis, the sensor exhibits high
polarisation sensitivity for a specific wavelength band, providing the possibility of directional measurements.
The realization of a DNA biosensor based on Double Tilted Fiber Bragg Grating (DTFBG) for label-free detection has
been demonstrated. To our knowledge this is the first time that a biosensor has been realized with such kind of device.
The surface of the optical fiber has been functionalized with peptide nucleic acid (PNA) in order to capture DNA
strands. The changes of the interference fringes visibility of the grating, due to the PNA-DNA binding, proved the
occurred fiber hybridization. The re-use of the fiber for multiple measurements and the selectivity of the sensor have
been also investigated.
We have recently introduced a new approach in the utilisation and actuation of liquid matrices inside microstructured
optical fibers, by infiltrating in their capillaries magnetically active fluids, namely, ferrofluids. The specific optofluidic
approach provides the possibility of actuation of the infiltrated liquid by applying an external magnetic field, thus,
exhibiting magnetofluidic capabilities. We apply this infiltration protocol in microstructured optical fiber Bragg gratings
for developing magnetic field tunable/sensitive photonic devices and sensing probes. The material and implementation
considerations related to this infiltration approach of viscous and opaque ferrofluids inside microstructured optical fibers,
and the corresponding effects on the guiding and scattering behavior of the microstructured optical fiber Bragg gratings
are presented and discussed. An updated review on this infiltrated microstructured optical fiber devices will be presented,
focusing on the demonstration of simple magnetofluidic configurations such as "on-off" Bragg grating trimmers, "infiber"
magnetometers, ferrofluidic defected Bragg reflectors and external magnetic field modulators. The design
principles of such "in-fiber" magnetofluidic photonic devices will be analysed, along with their particular functionalities
and application prospects; while in addition, the infiltration and fiber capillary functionalisation processes will be